Model systems are known to be useful in connection with various biological studies or in clinical application such as liver dialysis. For instance, a model system may be developed to mimic skin tissue in order to study the migration of carcinogens through the skin. However, a problem exists with respect to many known biological model systems in that known models have been unable to facilitate transfer of fluid materials between and among cells once cell growth reaches a certain thickness or density. In effect, fluids are unable to penetrate a thicker concentration of cells or a denser scaffold/base. This deficiency is a particular area of concern because a high concentration of cells can more closely mimic an in vivo tissue environment.
Accordingly, a need exists for ex vivo and in vitro systems that can provide an environment for concentrated cell or tissue growth and simultaneously facilitate transportation of fluids between and among cells in the system.